It is week nine on the Alternative Vote campaign trail, Yes supporters hold an event – which they call a flash mob – in London’s Trafalgar Square, but it’s not exactly unified – a bit like those who run the government.

Coalition partners, the Liberal Democrats, are the strongest supports of voting reform. But they think that those on the No side, cabinet colleagues included, are employing dirty, rough-house tactics.

In the Independent on Sunday, Lib Dem leader Nick Clegg denounced the No camp for its “lies, misinformation and deceit”.

‘Robust debate is normal in British politics… persistent resort to falsehoods is not’ – Chris Huhne

He said he hoped the vote would kill off a “nasty right wing clique” and mentions “David Cameron, Nick Griffin (the BNP chairman) – and whoever leads the Communist Party” as men who are “defending the indefensible.”

The Energy Secretary Chris Huhne is not happy either.

“Robust debate is normal in British politics” he wrote in a letter to the Chancellor George Osborne but “persistent resort to falsehoods is not.”

What’s really irritated the Yes camp is a claim by Mr Osborne and co about the costs of an AV system.

Lib Dem MP Simon Hughes said that people from the Prime Minister downwards were making arguments that were clearly not true.

People from the PM downwards make arguments that are clearly not true. He pointed to a No campaign leaflet that said switching to AV would cost £130m more due to electronic vote counting machines.

Simon Hughes said “there will be no electronic vote counting machines in the new system. You count just in the same way”.

The costs of counting votes is just one of several disputes between the two sides Mr Hughes says he’ll talk to the elections regulator about it. Chris Huhne went further today – he’s threatening legal action.

What do the no camp make of it?

Emily Thornburry, Labour MP for Islington South and Finsbury, said “we all agree that one thing Lib Dems do do, is they fight dirty. So for them to be howling and saying it’s not fight is a bit of a laugh really.”

The wrapping’s come off this Easter the battle more sour than sweet, this ferocity betrays an increasing close fight.

Two weeks ago 40 per cent backed the No campaign – while those supporting yes trailed by 6 points. Later polls showed the No campaign gaining ground – at one point registering 48 per cent.

However, the most recent poll showed a much tighter race – with just two percentage points separating both sides.

AV: to vote Yes or No?

As the date for the referendum on changing the way this country elects government in approaches, Channel 4 News approaches both sides of the debate asking them to make their case for the public's vote on May 5.

That Rose Garden moment when Nick Clegg and David Cameron appeared together, is fading into the distance.

The Prime Minister and his Deputy have fallen out – or at least they’re less likely to play tennis with each other in the future. The business of government is going to get tougher, and Cabinet meetings a little more uncomfortable.